Sema: Use protocol generic signature instead of requirement signature to check type witnesses
Sema: Use protocol generic signature instead of requirement signature to check type witnesses

Regression was introduced by
ec60c88412c4b858d687185ec5202ac995fa28f7.

I don't have a reduced test case, but this solves
<rdar://problem/32668454>.

gribozavr/swift,OscarSwanros/swift,allevato/swift,natecook1000/swift,gribozavr/swift,CodaFi/swift,austinzheng/swift,xwu/swift,austinzheng/swift,harlanhaskins/swift,amraboelela/swift,benlangmuir/swift,brentdax/swift,rudkx/swift,djwbrown/swift,tkremenek/swift,deyton/swift,jckarter/swift,ahoppen/swift,zisko/swift,jmgc/swift,amraboelela/swift,uasys/swift,parkera/swift,xwu/swift,practicalswift/swift,tkremenek/swift,return/swift,parkera/swift,karwa/swift,CodaFi/swift,zisko/swift,jckarter/swift,deyton/swift,gribozavr/swift,gregomni/swift,rudkx/swift,gribozavr/swift,hooman/swift,huonw/swift,karwa/swift,jmgc/swift,benlangmuir/swift,swiftix/swift,lorentey/swift,lorentey/swift,ahoppen/swift,tkremenek/swift,aschwaighofer/swift,rudkx/swift,karwa/swift,austinzheng/swift,sschiau/swift,benlangmuir/swift,nathawes/swift,felix91gr/swift,shajrawi/swift,airspeedswift/swift,atrick/swift,harlanhaskins/swift,gregomni/swift,jopamer/swift,brentdax/swift,jckarter/swift,natecook1000/swift,allevato/swift,danielmartin/swift,karwa/swift,apple/swift,OscarSwanros/swift,parkera/swift,jmgc/swift,harlanhaskins/swift,huonw/swift,natecook1000/swift,deyton/swift,airspeedswift/swift,benlangmuir/swift,swiftix/swift,jckarter/swift,alblue/swift,jopamer/swift,roambotics/swift,practicalswift/swift,sschiau/swift,shahmishal/swift,shajrawi/swift,jopamer/swift,natecook1000/swift,harlanhaskins/swift,apple/swift,stephentyrone/swift,OscarSwanros/swift,swiftix/swift,nathawes/swift,lorentey/swift,hughbe/swift,milseman/swift,devincoughlin/swift,parkera/swift,sschiau/swift,apple/swift,sschiau/swift,hughbe/swift,apple/swift,jmgc/swift,shajrawi/swift,JGiola/swift,aschwaighofer/swift,allevato/swift,tkremenek/swift,gregomni/swift,sschiau/swift,zisko/swift,xwu/swift,austinzheng/swift,atrick/swift,milseman/swift,danielmartin/swift,danielmartin/swift,felix91gr/swift,stephentyrone/swift,apple/swift,allevato/swift,hughbe/swift,frootloops/swift,jckarter/swift,deyton/swift,devincoughlin/swift,CodaFi/swift,austinzheng/swift,tjw/swift,huonw/swift,roambotics/swift,tjw/swift,jmgc/swift,JGiola/swift,gribozavr/swift,CodaFi/swift,swiftix/swift,jmgc/swift,practicalswift/swift,stephentyrone/swift,devincoughlin/swift,austinzheng/swift,parkera/swift,lorentey/swift,shahmishal/swift,uasys/swift,djwbrown/swift,danielmartin/swift,deyton/swift,xedin/swift,sschiau/swift,gregomni/swift,karwa/swift,devincoughlin/swift,JGiola/swift,return/swift,lorentey/swift,roambotics/swift,devincoughlin/swift,djwbrown/swift,zisko/swift,felix91gr/swift,felix91gr/swift,aschwaighofer/swift,natecook1000/swift,frootloops/swift,hooman/swift,danielmartin/swift,uasys/swift,return/swift,uasys/swift,airspeedswift/swift,aschwaighofer/swift,tjw/swift,roambotics/swift,zisko/swift,frootloops/swift,allevato/swift,hughbe/swift,tkremenek/swift,glessard/swift,shajrawi/swift,allevato/swift,return/swift,JGiola/swift,glessard/swift,frootloops/swift,roambotics/swift,lorentey/swift,brentdax/swift,gregomni/swift,CodaFi/swift,harlanhaskins/swift,uasys/swift,shahmishal/swift,gribozavr/swift,devincoughlin/swift,amraboelela/swift,airspeedswift/swift,rudkx/swift,nathawes/swift,JGiola/swift,amraboelela/swift,aschwaighofer/swift,alblue/swift,gribozavr/swift,stephentyrone/swift,parkera/swift,roambotics/swift,zisko/swift,stephentyrone/swift,xwu/swift,rudkx/swift,devincoughlin/swift,glessard/swift,airspeedswift/swift,CodaFi/swift,nathawes/swift,xwu/swift,benlangmuir/swift,return/swift,return/swift,atrick/swift,amraboelela/swift,hooman/swift,milseman/swift,jckarter/swift,jopamer/swift,tkremenek/swift,practicalswift/swift,harlanhaskins/swift,djwbrown/swift,uasys/swift,harlanhaskins/swift,hooman/swift,amraboelela/swift,xwu/swift,OscarSwanros/swift,austinzheng/swift,karwa/swift,alblue/swift,swiftix/swift,xedin/swift,sschiau/swift,tjw/swift,glessard/swift,rudkx/swift,parkera/swift,danielmartin/swift,milseman/swift,xedin/swift,gregomni/swift,ahoppen/swift,gribozavr/swift,apple/swift,hughbe/swift,OscarSwanros/swift,devincoughlin/swift,deyton/swift,frootloops/swift,jmgc/swift,practicalswift/swift,OscarSwanros/swift,karwa/swift,felix91gr/swift,shahmishal/swift,practicalswift/swift,atrick/swift,tjw/swift,swiftix/swift,jopamer/swift,jopamer/swift,brentdax/swift,tjw/swift,OscarSwanros/swift,lorentey/swift,jopamer/swift,alblue/swift,alblue/swift,CodaFi/swift,glessard/swift,huonw/swift,swiftix/swift,karwa/swift,shajrawi/swift,nathawes/swift,atrick/swift,nathawes/swift,allevato/swift,shahmishal/swift,danielmartin/swift,xedin/swift,felix91gr/swift,brentdax/swift,huonw/swift,stephentyrone/swift,nathawes/swift,shajrawi/swift,JGiola/swift,deyton/swift,milseman/swift,tjw/swift,sschiau/swift,hooman/swift,ahoppen/swift,felix91gr/swift,xedin/swift,airspeedswift/swift,stephentyrone/swift,benlangmuir/swift,hughbe/swift,amraboelela/swift,shajrawi/swift,parkera/swift,hooman/swift,aschwaighofer/swift,frootloops/swift,milseman/swift,hooman/swift,natecook1000/swift,huonw/swift,natecook1000/swift,lorentey/swift,djwbrown/swift,brentdax/swift,xedin/swift,alblue/swift,milseman/swift,xwu/swift,frootloops/swift,shahmishal/swift,practicalswift/swift,alblue/swift,shajrawi/swift,huonw/swift,uasys/swift,brentdax/swift,djwbrown/swift,jckarter/swift,tkremenek/swift,aschwaighofer/swift,shahmishal/swift,hughbe/swift,shahmishal/swift,zisko/swift,glessard/swift,atrick/swift,airspeedswift/swift,xedin/swift,djwbrown/swift,ahoppen/swift,practicalswift/swift,return/swift,ahoppen/swift,xedin/swift